Ways of Improving the Interfacial Durability of Silicone Adhesives in Building Applications

Beyond their application as sealants, silicone formulations are used as adhesives in insulated glass and structural glazing applications. The adhesion durability of such assemblies is a function of both the adhesion at the glass-interface surfaces and the internal cohesion of the adhesive. Failure in the bulk of the adhesive will occur if external stresses exceed the ultimate strength of the adhesive or when the movement capability of the adhesive is lower than required by the application. The most often observed reasons for failure are, however, substrate-adhesive interface ruptures. If similar silicone adhesives are used in different building projects, the substrates can vary widely, leading to many different interfaces. Interface adhesion can be improved by modifying the substrate surface, modifying the adhesive formulation, or using a primer. In this work, improved adhesion durability on different substrates will be shown with an improved version of a two-part silicone adhesive used for insulated glass and structural glazing applications, which was introduced in Europe in 2010. Results without primer and with the use of either a wet primer or a dry SiOx (Pyrosil®) flame treatment will be shown. Adhesion durability after water immersion, UV irradiation, and high humidity will be reported for new low E insulated glass coatings, powder coated aluminum, stainless steel, and some other standard building substrates.